The present invention relates to the art of wheel balancers. More particularly, the present invention relates to an electro-mechanical wheel balancer having a laser-assisted weight placement system.
Electro-mechanical wheel balancers have been well known in the vehicle repair trade for many years. These machines often include a chassis in the form of a cabinet in which various components and systems are housed. An imbalanced wheel is attached to a rotatable shaft that extends from the chassis, typically using various mounting cones or other adapters. The shaft is rotatably driven by a suitable drive system (such as a direct drive motor) to create a dynamic imbalance condition. In addition, prior art balancing systems have included an A&D arm that assists in measuring the wheel and determining the locations of the corrective weights. These machines have further included sensors to detect the wheel imbalance forces and electronic circuitry to analyze the forces and display an amount of weight needed to balance the wheel.
It is well known in the art to attach corrective weights (typically clip weights) of various masses to the outer and inner flange of a wheel to balance the wheel. After spinning the wheel to determine the dynamic imbalance, if any, the wheel balancer may resolve the imbalance vector into two opposite vectors corresponding to the positions on the two wheel flanges (outer and inner) where the weights are to be placed.
When using this type of balancer, the operator defines the locations where the corrective weights can be applied by using the A&D arm. The machine then rotates the wheel mass and calculates an effective amount of corrective weight based on the available locations inputted by the user and the wheel's imbalance characteristics. Next, the operator places a corrective weight at top dead center on each of the flanges in an amount calculated by the machine.
The recent development of wheels without flanges has complicated the operator's task of installing corrective weights. When balancing wheels without flanges, the weights may need to be placed in “hidden” locations on the wheel. In many situations, one corrective weight (a clip weight) is placed on the inner flange of the wheel and another weight (an adhesive weight) is attached to the inner surface of the wheel hub in a plane just behind the spokes or center disk of the wheel. The closer proximity of the corrective planes in this configuration may require that the weights be larger and more accurately placed on the wheel.
A challenge in placing hidden weights on the inner surface of the wheel is accurately placing the weight at the location prescribed by the machine. If the adhesive weight is mislocated, then the wheel will show an imbalance when a check spin is performed. Attaching adhesive weights is also complicated by difficulties in locating the proper radial position for the clip weight on the interior flange and freeing the area of the adhesive weight of grease, typically near the 12 o'clock position on the wheel's inner surface. Because the adhesive weights are one-time use only, replacing and discarding mislocated weights can lead to additional expense. Thus, correctly placing the weight on the first attempt may help reduce time and cost.
Many attempts to solve the above-mentioned problems have been made. For example, some balancer manufacturers have provided an arm which assists in mounting the corrective adhesive weight. These systems are often cumbersome because the weight needs to be attached near the 12 o'clock position and is therefore not visible to the operator during placement.
Other prior art techniques include the following: (1) The use of a laser over the top of the tire that creates a line across the top of the tire to help the operator in placing the corrective weight at top dead center. (2) Brakes on the wheel spindle to help the operator in placement of the corrective weights at top dead center. (3) Alone or in combination with (2), a measuring arm that stops at the correct inboard outboard location to help the operator in placing the weight at top dead center. (4) An audible sound buzzer to help the operator in placing the corrective weight at the proper location. (5) An arm that places the weight on the wheel at the correct location. When the wheel stops after the first spin, the operator places the correct amount of weight in the A&D arm device and it automatically places the weight at the correct location on the wheel rim.
Another prior art method uses a laser to guide the operator to the location on the inside of the wheel where the weight is to be placed. The placement of the laser beam is accomplished with the help of a mechanical servo system. The laser is mounted to the end of a small tube that translates in and out of the inside of the wheel. The operator positions the laser with the wheel stopped before the balance spin. Just before the balance spin, the laser retracts and allows the wheel to spin. Once the balancer determines the imbalance of the wheel and the wheel stops spinning, the tube system holding the laser re-extends to the set position to assist the operator in locating the correct adhesive weight location.